Conventionally, a head-mounted type display (hereinafter, referred to as head mount display (HMD)) is known. As an image display apparatus used for the HMD, the following configurations in which an image can be displayed in front of the eyes of the user have been disclosed.
For example, Patent Document 1 describes a virtual-image display apparatus (image display apparatus). The virtual-image display apparatus (image display apparatus) for enabling a viewer to view a two-dimensional image, which is formed by an image formation apparatus, as an enlarged image through a virtual-image optical system.
Further, for example, Patent Document 2 describes a virtual-image display apparatus (image display apparatus) using a hologram diffraction grating in order to enable the viewer to view a two-dimensional image, which is formed by an image formation apparatus, as an enlarged image through a virtual-image optical system.
By the way, if mounted on the user's head or the like as the HMD, the image display apparatus may be attached to an eyeglasses-shaped frame (see FIG. 30 or the like in Patent Document 3). As described in Patent Document 3, in the HMD, the viewer feels fatigue if the spatial position of an image generated from light emitted from a light guiding means of the image display apparatus changes due to shape change or the like of the frame when worn.
In addition, Patent Document 3 describes an HMD in which two left and right image display apparatuses are coupled through a coupling member separate from the eyeglasses-shaped frame, as a means for solving the problem above.
Patent Document 1: Japanese Patent Application Laid-open No. 2006-162767
Patent Document 2: Japanese Patent Application Laid-open No. 2007-94175
Patent Document 3: Japanese Patent Application Laid-open No. 2010-145859